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Diffstat (limited to 'fs/xfs/xfs_dir2_readdir.c')
-rw-r--r--fs/xfs/xfs_dir2_readdir.c681
1 files changed, 681 insertions, 0 deletions
diff --git a/fs/xfs/xfs_dir2_readdir.c b/fs/xfs/xfs_dir2_readdir.c
new file mode 100644
index 000000000..098cd78fe
--- /dev/null
+++ b/fs/xfs/xfs_dir2_readdir.c
@@ -0,0 +1,681 @@
+/*
+ * Copyright (c) 2000-2005 Silicon Graphics, Inc.
+ * Copyright (c) 2013 Red Hat, Inc.
+ * All Rights Reserved.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License as
+ * published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it would be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
+ */
+#include "xfs.h"
+#include "xfs_fs.h"
+#include "xfs_format.h"
+#include "xfs_log_format.h"
+#include "xfs_trans_resv.h"
+#include "xfs_bit.h"
+#include "xfs_mount.h"
+#include "xfs_da_format.h"
+#include "xfs_da_btree.h"
+#include "xfs_inode.h"
+#include "xfs_dir2.h"
+#include "xfs_dir2_priv.h"
+#include "xfs_error.h"
+#include "xfs_trace.h"
+#include "xfs_bmap.h"
+#include "xfs_trans.h"
+
+/*
+ * Directory file type support functions
+ */
+static unsigned char xfs_dir3_filetype_table[] = {
+ DT_UNKNOWN, DT_REG, DT_DIR, DT_CHR, DT_BLK,
+ DT_FIFO, DT_SOCK, DT_LNK, DT_WHT,
+};
+
+static unsigned char
+xfs_dir3_get_dtype(
+ struct xfs_mount *mp,
+ __uint8_t filetype)
+{
+ if (!xfs_sb_version_hasftype(&mp->m_sb))
+ return DT_UNKNOWN;
+
+ if (filetype >= XFS_DIR3_FT_MAX)
+ return DT_UNKNOWN;
+
+ return xfs_dir3_filetype_table[filetype];
+}
+
+STATIC int
+xfs_dir2_sf_getdents(
+ struct xfs_da_args *args,
+ struct dir_context *ctx)
+{
+ int i; /* shortform entry number */
+ struct xfs_inode *dp = args->dp; /* incore directory inode */
+ xfs_dir2_dataptr_t off; /* current entry's offset */
+ xfs_dir2_sf_entry_t *sfep; /* shortform directory entry */
+ xfs_dir2_sf_hdr_t *sfp; /* shortform structure */
+ xfs_dir2_dataptr_t dot_offset;
+ xfs_dir2_dataptr_t dotdot_offset;
+ xfs_ino_t ino;
+ struct xfs_da_geometry *geo = args->geo;
+
+ ASSERT(dp->i_df.if_flags & XFS_IFINLINE);
+ /*
+ * Give up if the directory is way too short.
+ */
+ if (dp->i_d.di_size < offsetof(xfs_dir2_sf_hdr_t, parent)) {
+ ASSERT(XFS_FORCED_SHUTDOWN(dp->i_mount));
+ return -EIO;
+ }
+
+ ASSERT(dp->i_df.if_bytes == dp->i_d.di_size);
+ ASSERT(dp->i_df.if_u1.if_data != NULL);
+
+ sfp = (xfs_dir2_sf_hdr_t *)dp->i_df.if_u1.if_data;
+
+ ASSERT(dp->i_d.di_size >= xfs_dir2_sf_hdr_size(sfp->i8count));
+
+ /*
+ * If the block number in the offset is out of range, we're done.
+ */
+ if (xfs_dir2_dataptr_to_db(geo, ctx->pos) > geo->datablk)
+ return 0;
+
+ /*
+ * Precalculate offsets for . and .. as we will always need them.
+ *
+ * XXX(hch): the second argument is sometimes 0 and sometimes
+ * geo->datablk
+ */
+ dot_offset = xfs_dir2_db_off_to_dataptr(geo, geo->datablk,
+ dp->d_ops->data_dot_offset);
+ dotdot_offset = xfs_dir2_db_off_to_dataptr(geo, geo->datablk,
+ dp->d_ops->data_dotdot_offset);
+
+ /*
+ * Put . entry unless we're starting past it.
+ */
+ if (ctx->pos <= dot_offset) {
+ ctx->pos = dot_offset & 0x7fffffff;
+ if (!dir_emit(ctx, ".", 1, dp->i_ino, DT_DIR))
+ return 0;
+ }
+
+ /*
+ * Put .. entry unless we're starting past it.
+ */
+ if (ctx->pos <= dotdot_offset) {
+ ino = dp->d_ops->sf_get_parent_ino(sfp);
+ ctx->pos = dotdot_offset & 0x7fffffff;
+ if (!dir_emit(ctx, "..", 2, ino, DT_DIR))
+ return 0;
+ }
+
+ /*
+ * Loop while there are more entries and put'ing works.
+ */
+ sfep = xfs_dir2_sf_firstentry(sfp);
+ for (i = 0; i < sfp->count; i++) {
+ __uint8_t filetype;
+
+ off = xfs_dir2_db_off_to_dataptr(geo, geo->datablk,
+ xfs_dir2_sf_get_offset(sfep));
+
+ if (ctx->pos > off) {
+ sfep = dp->d_ops->sf_nextentry(sfp, sfep);
+ continue;
+ }
+
+ ino = dp->d_ops->sf_get_ino(sfp, sfep);
+ filetype = dp->d_ops->sf_get_ftype(sfep);
+ ctx->pos = off & 0x7fffffff;
+ if (!dir_emit(ctx, (char *)sfep->name, sfep->namelen, ino,
+ xfs_dir3_get_dtype(dp->i_mount, filetype)))
+ return 0;
+ sfep = dp->d_ops->sf_nextentry(sfp, sfep);
+ }
+
+ ctx->pos = xfs_dir2_db_off_to_dataptr(geo, geo->datablk + 1, 0) &
+ 0x7fffffff;
+ return 0;
+}
+
+/*
+ * Readdir for block directories.
+ */
+STATIC int
+xfs_dir2_block_getdents(
+ struct xfs_da_args *args,
+ struct dir_context *ctx)
+{
+ struct xfs_inode *dp = args->dp; /* incore directory inode */
+ xfs_dir2_data_hdr_t *hdr; /* block header */
+ struct xfs_buf *bp; /* buffer for block */
+ xfs_dir2_block_tail_t *btp; /* block tail */
+ xfs_dir2_data_entry_t *dep; /* block data entry */
+ xfs_dir2_data_unused_t *dup; /* block unused entry */
+ char *endptr; /* end of the data entries */
+ int error; /* error return value */
+ char *ptr; /* current data entry */
+ int wantoff; /* starting block offset */
+ xfs_off_t cook;
+ struct xfs_da_geometry *geo = args->geo;
+
+ /*
+ * If the block number in the offset is out of range, we're done.
+ */
+ if (xfs_dir2_dataptr_to_db(geo, ctx->pos) > geo->datablk)
+ return 0;
+
+ error = xfs_dir3_block_read(NULL, dp, &bp);
+ if (error)
+ return error;
+
+ /*
+ * Extract the byte offset we start at from the seek pointer.
+ * We'll skip entries before this.
+ */
+ wantoff = xfs_dir2_dataptr_to_off(geo, ctx->pos);
+ hdr = bp->b_addr;
+ xfs_dir3_data_check(dp, bp);
+ /*
+ * Set up values for the loop.
+ */
+ btp = xfs_dir2_block_tail_p(geo, hdr);
+ ptr = (char *)dp->d_ops->data_entry_p(hdr);
+ endptr = (char *)xfs_dir2_block_leaf_p(btp);
+
+ /*
+ * Loop over the data portion of the block.
+ * Each object is a real entry (dep) or an unused one (dup).
+ */
+ while (ptr < endptr) {
+ __uint8_t filetype;
+
+ dup = (xfs_dir2_data_unused_t *)ptr;
+ /*
+ * Unused, skip it.
+ */
+ if (be16_to_cpu(dup->freetag) == XFS_DIR2_DATA_FREE_TAG) {
+ ptr += be16_to_cpu(dup->length);
+ continue;
+ }
+
+ dep = (xfs_dir2_data_entry_t *)ptr;
+
+ /*
+ * Bump pointer for the next iteration.
+ */
+ ptr += dp->d_ops->data_entsize(dep->namelen);
+ /*
+ * The entry is before the desired starting point, skip it.
+ */
+ if ((char *)dep - (char *)hdr < wantoff)
+ continue;
+
+ cook = xfs_dir2_db_off_to_dataptr(geo, geo->datablk,
+ (char *)dep - (char *)hdr);
+
+ ctx->pos = cook & 0x7fffffff;
+ filetype = dp->d_ops->data_get_ftype(dep);
+ /*
+ * If it didn't fit, set the final offset to here & return.
+ */
+ if (!dir_emit(ctx, (char *)dep->name, dep->namelen,
+ be64_to_cpu(dep->inumber),
+ xfs_dir3_get_dtype(dp->i_mount, filetype))) {
+ xfs_trans_brelse(NULL, bp);
+ return 0;
+ }
+ }
+
+ /*
+ * Reached the end of the block.
+ * Set the offset to a non-existent block 1 and return.
+ */
+ ctx->pos = xfs_dir2_db_off_to_dataptr(geo, geo->datablk + 1, 0) &
+ 0x7fffffff;
+ xfs_trans_brelse(NULL, bp);
+ return 0;
+}
+
+struct xfs_dir2_leaf_map_info {
+ xfs_extlen_t map_blocks; /* number of fsbs in map */
+ xfs_dablk_t map_off; /* last mapped file offset */
+ int map_size; /* total entries in *map */
+ int map_valid; /* valid entries in *map */
+ int nmap; /* mappings to ask xfs_bmapi */
+ xfs_dir2_db_t curdb; /* db for current block */
+ int ra_current; /* number of read-ahead blks */
+ int ra_index; /* *map index for read-ahead */
+ int ra_offset; /* map entry offset for ra */
+ int ra_want; /* readahead count wanted */
+ struct xfs_bmbt_irec map[]; /* map vector for blocks */
+};
+
+STATIC int
+xfs_dir2_leaf_readbuf(
+ struct xfs_da_args *args,
+ size_t bufsize,
+ struct xfs_dir2_leaf_map_info *mip,
+ xfs_dir2_off_t *curoff,
+ struct xfs_buf **bpp)
+{
+ struct xfs_inode *dp = args->dp;
+ struct xfs_buf *bp = *bpp;
+ struct xfs_bmbt_irec *map = mip->map;
+ struct blk_plug plug;
+ int error = 0;
+ int length;
+ int i;
+ int j;
+ struct xfs_da_geometry *geo = args->geo;
+
+ /*
+ * If we have a buffer, we need to release it and
+ * take it out of the mapping.
+ */
+
+ if (bp) {
+ xfs_trans_brelse(NULL, bp);
+ bp = NULL;
+ mip->map_blocks -= geo->fsbcount;
+ /*
+ * Loop to get rid of the extents for the
+ * directory block.
+ */
+ for (i = geo->fsbcount; i > 0; ) {
+ j = min_t(int, map->br_blockcount, i);
+ map->br_blockcount -= j;
+ map->br_startblock += j;
+ map->br_startoff += j;
+ /*
+ * If mapping is done, pitch it from
+ * the table.
+ */
+ if (!map->br_blockcount && --mip->map_valid)
+ memmove(&map[0], &map[1],
+ sizeof(map[0]) * mip->map_valid);
+ i -= j;
+ }
+ }
+
+ /*
+ * Recalculate the readahead blocks wanted.
+ */
+ mip->ra_want = howmany(bufsize + geo->blksize, (1 << geo->fsblog)) - 1;
+ ASSERT(mip->ra_want >= 0);
+
+ /*
+ * If we don't have as many as we want, and we haven't
+ * run out of data blocks, get some more mappings.
+ */
+ if (1 + mip->ra_want > mip->map_blocks &&
+ mip->map_off < xfs_dir2_byte_to_da(geo, XFS_DIR2_LEAF_OFFSET)) {
+ /*
+ * Get more bmaps, fill in after the ones
+ * we already have in the table.
+ */
+ mip->nmap = mip->map_size - mip->map_valid;
+ error = xfs_bmapi_read(dp, mip->map_off,
+ xfs_dir2_byte_to_da(geo, XFS_DIR2_LEAF_OFFSET) -
+ mip->map_off,
+ &map[mip->map_valid], &mip->nmap, 0);
+
+ /*
+ * Don't know if we should ignore this or try to return an
+ * error. The trouble with returning errors is that readdir
+ * will just stop without actually passing the error through.
+ */
+ if (error)
+ goto out; /* XXX */
+
+ /*
+ * If we got all the mappings we asked for, set the final map
+ * offset based on the last bmap value received. Otherwise,
+ * we've reached the end.
+ */
+ if (mip->nmap == mip->map_size - mip->map_valid) {
+ i = mip->map_valid + mip->nmap - 1;
+ mip->map_off = map[i].br_startoff + map[i].br_blockcount;
+ } else
+ mip->map_off = xfs_dir2_byte_to_da(geo,
+ XFS_DIR2_LEAF_OFFSET);
+
+ /*
+ * Look for holes in the mapping, and eliminate them. Count up
+ * the valid blocks.
+ */
+ for (i = mip->map_valid; i < mip->map_valid + mip->nmap; ) {
+ if (map[i].br_startblock == HOLESTARTBLOCK) {
+ mip->nmap--;
+ length = mip->map_valid + mip->nmap - i;
+ if (length)
+ memmove(&map[i], &map[i + 1],
+ sizeof(map[i]) * length);
+ } else {
+ mip->map_blocks += map[i].br_blockcount;
+ i++;
+ }
+ }
+ mip->map_valid += mip->nmap;
+ }
+
+ /*
+ * No valid mappings, so no more data blocks.
+ */
+ if (!mip->map_valid) {
+ *curoff = xfs_dir2_da_to_byte(geo, mip->map_off);
+ goto out;
+ }
+
+ /*
+ * Read the directory block starting at the first mapping.
+ */
+ mip->curdb = xfs_dir2_da_to_db(geo, map->br_startoff);
+ error = xfs_dir3_data_read(NULL, dp, map->br_startoff,
+ map->br_blockcount >= geo->fsbcount ?
+ XFS_FSB_TO_DADDR(dp->i_mount, map->br_startblock) :
+ -1, &bp);
+ /*
+ * Should just skip over the data block instead of giving up.
+ */
+ if (error)
+ goto out; /* XXX */
+
+ /*
+ * Adjust the current amount of read-ahead: we just read a block that
+ * was previously ra.
+ */
+ if (mip->ra_current)
+ mip->ra_current -= geo->fsbcount;
+
+ /*
+ * Do we need more readahead?
+ */
+ blk_start_plug(&plug);
+ for (mip->ra_index = mip->ra_offset = i = 0;
+ mip->ra_want > mip->ra_current && i < mip->map_blocks;
+ i += geo->fsbcount) {
+ ASSERT(mip->ra_index < mip->map_valid);
+ /*
+ * Read-ahead a contiguous directory block.
+ */
+ if (i > mip->ra_current &&
+ map[mip->ra_index].br_blockcount >= geo->fsbcount) {
+ xfs_dir3_data_readahead(dp,
+ map[mip->ra_index].br_startoff + mip->ra_offset,
+ XFS_FSB_TO_DADDR(dp->i_mount,
+ map[mip->ra_index].br_startblock +
+ mip->ra_offset));
+ mip->ra_current = i;
+ }
+
+ /*
+ * Read-ahead a non-contiguous directory block. This doesn't
+ * use our mapping, but this is a very rare case.
+ */
+ else if (i > mip->ra_current) {
+ xfs_dir3_data_readahead(dp,
+ map[mip->ra_index].br_startoff +
+ mip->ra_offset, -1);
+ mip->ra_current = i;
+ }
+
+ /*
+ * Advance offset through the mapping table.
+ */
+ for (j = 0; j < geo->fsbcount; j += length ) {
+ /*
+ * The rest of this extent but not more than a dir
+ * block.
+ */
+ length = min_t(int, geo->fsbcount,
+ map[mip->ra_index].br_blockcount -
+ mip->ra_offset);
+ mip->ra_offset += length;
+
+ /*
+ * Advance to the next mapping if this one is used up.
+ */
+ if (mip->ra_offset == map[mip->ra_index].br_blockcount) {
+ mip->ra_offset = 0;
+ mip->ra_index++;
+ }
+ }
+ }
+ blk_finish_plug(&plug);
+
+out:
+ *bpp = bp;
+ return error;
+}
+
+/*
+ * Getdents (readdir) for leaf and node directories.
+ * This reads the data blocks only, so is the same for both forms.
+ */
+STATIC int
+xfs_dir2_leaf_getdents(
+ struct xfs_da_args *args,
+ struct dir_context *ctx,
+ size_t bufsize)
+{
+ struct xfs_inode *dp = args->dp;
+ struct xfs_buf *bp = NULL; /* data block buffer */
+ xfs_dir2_data_hdr_t *hdr; /* data block header */
+ xfs_dir2_data_entry_t *dep; /* data entry */
+ xfs_dir2_data_unused_t *dup; /* unused entry */
+ int error = 0; /* error return value */
+ int length; /* temporary length value */
+ int byteoff; /* offset in current block */
+ xfs_dir2_off_t curoff; /* current overall offset */
+ xfs_dir2_off_t newoff; /* new curoff after new blk */
+ char *ptr = NULL; /* pointer to current data */
+ struct xfs_dir2_leaf_map_info *map_info;
+ struct xfs_da_geometry *geo = args->geo;
+
+ /*
+ * If the offset is at or past the largest allowed value,
+ * give up right away.
+ */
+ if (ctx->pos >= XFS_DIR2_MAX_DATAPTR)
+ return 0;
+
+ /*
+ * Set up to bmap a number of blocks based on the caller's
+ * buffer size, the directory block size, and the filesystem
+ * block size.
+ */
+ length = howmany(bufsize + geo->blksize, (1 << geo->fsblog));
+ map_info = kmem_zalloc(offsetof(struct xfs_dir2_leaf_map_info, map) +
+ (length * sizeof(struct xfs_bmbt_irec)),
+ KM_SLEEP | KM_NOFS);
+ map_info->map_size = length;
+
+ /*
+ * Inside the loop we keep the main offset value as a byte offset
+ * in the directory file.
+ */
+ curoff = xfs_dir2_dataptr_to_byte(ctx->pos);
+
+ /*
+ * Force this conversion through db so we truncate the offset
+ * down to get the start of the data block.
+ */
+ map_info->map_off = xfs_dir2_db_to_da(geo,
+ xfs_dir2_byte_to_db(geo, curoff));
+
+ /*
+ * Loop over directory entries until we reach the end offset.
+ * Get more blocks and readahead as necessary.
+ */
+ while (curoff < XFS_DIR2_LEAF_OFFSET) {
+ __uint8_t filetype;
+
+ /*
+ * If we have no buffer, or we're off the end of the
+ * current buffer, need to get another one.
+ */
+ if (!bp || ptr >= (char *)bp->b_addr + geo->blksize) {
+
+ error = xfs_dir2_leaf_readbuf(args, bufsize, map_info,
+ &curoff, &bp);
+ if (error || !map_info->map_valid)
+ break;
+
+ /*
+ * Having done a read, we need to set a new offset.
+ */
+ newoff = xfs_dir2_db_off_to_byte(geo,
+ map_info->curdb, 0);
+ /*
+ * Start of the current block.
+ */
+ if (curoff < newoff)
+ curoff = newoff;
+ /*
+ * Make sure we're in the right block.
+ */
+ else if (curoff > newoff)
+ ASSERT(xfs_dir2_byte_to_db(geo, curoff) ==
+ map_info->curdb);
+ hdr = bp->b_addr;
+ xfs_dir3_data_check(dp, bp);
+ /*
+ * Find our position in the block.
+ */
+ ptr = (char *)dp->d_ops->data_entry_p(hdr);
+ byteoff = xfs_dir2_byte_to_off(geo, curoff);
+ /*
+ * Skip past the header.
+ */
+ if (byteoff == 0)
+ curoff += dp->d_ops->data_entry_offset;
+ /*
+ * Skip past entries until we reach our offset.
+ */
+ else {
+ while ((char *)ptr - (char *)hdr < byteoff) {
+ dup = (xfs_dir2_data_unused_t *)ptr;
+
+ if (be16_to_cpu(dup->freetag)
+ == XFS_DIR2_DATA_FREE_TAG) {
+
+ length = be16_to_cpu(dup->length);
+ ptr += length;
+ continue;
+ }
+ dep = (xfs_dir2_data_entry_t *)ptr;
+ length =
+ dp->d_ops->data_entsize(dep->namelen);
+ ptr += length;
+ }
+ /*
+ * Now set our real offset.
+ */
+ curoff =
+ xfs_dir2_db_off_to_byte(geo,
+ xfs_dir2_byte_to_db(geo, curoff),
+ (char *)ptr - (char *)hdr);
+ if (ptr >= (char *)hdr + geo->blksize) {
+ continue;
+ }
+ }
+ }
+ /*
+ * We have a pointer to an entry.
+ * Is it a live one?
+ */
+ dup = (xfs_dir2_data_unused_t *)ptr;
+ /*
+ * No, it's unused, skip over it.
+ */
+ if (be16_to_cpu(dup->freetag) == XFS_DIR2_DATA_FREE_TAG) {
+ length = be16_to_cpu(dup->length);
+ ptr += length;
+ curoff += length;
+ continue;
+ }
+
+ dep = (xfs_dir2_data_entry_t *)ptr;
+ length = dp->d_ops->data_entsize(dep->namelen);
+ filetype = dp->d_ops->data_get_ftype(dep);
+
+ ctx->pos = xfs_dir2_byte_to_dataptr(curoff) & 0x7fffffff;
+ if (!dir_emit(ctx, (char *)dep->name, dep->namelen,
+ be64_to_cpu(dep->inumber),
+ xfs_dir3_get_dtype(dp->i_mount, filetype)))
+ break;
+
+ /*
+ * Advance to next entry in the block.
+ */
+ ptr += length;
+ curoff += length;
+ /* bufsize may have just been a guess; don't go negative */
+ bufsize = bufsize > length ? bufsize - length : 0;
+ }
+
+ /*
+ * All done. Set output offset value to current offset.
+ */
+ if (curoff > xfs_dir2_dataptr_to_byte(XFS_DIR2_MAX_DATAPTR))
+ ctx->pos = XFS_DIR2_MAX_DATAPTR & 0x7fffffff;
+ else
+ ctx->pos = xfs_dir2_byte_to_dataptr(curoff) & 0x7fffffff;
+ kmem_free(map_info);
+ if (bp)
+ xfs_trans_brelse(NULL, bp);
+ return error;
+}
+
+/*
+ * Read a directory.
+ */
+int
+xfs_readdir(
+ struct xfs_inode *dp,
+ struct dir_context *ctx,
+ size_t bufsize)
+{
+ struct xfs_da_args args = { NULL };
+ int rval;
+ int v;
+ uint lock_mode;
+
+ trace_xfs_readdir(dp);
+
+ if (XFS_FORCED_SHUTDOWN(dp->i_mount))
+ return -EIO;
+
+ ASSERT(S_ISDIR(dp->i_d.di_mode));
+ XFS_STATS_INC(xs_dir_getdents);
+
+ args.dp = dp;
+ args.geo = dp->i_mount->m_dir_geo;
+
+ lock_mode = xfs_ilock_data_map_shared(dp);
+ if (dp->i_d.di_format == XFS_DINODE_FMT_LOCAL)
+ rval = xfs_dir2_sf_getdents(&args, ctx);
+ else if ((rval = xfs_dir2_isblock(&args, &v)))
+ ;
+ else if (v)
+ rval = xfs_dir2_block_getdents(&args, ctx);
+ else
+ rval = xfs_dir2_leaf_getdents(&args, ctx, bufsize);
+ xfs_iunlock(dp, lock_mode);
+
+ return rval;
+}
generated by cgit v1.2.3-54-g00ecf (git 2.45.2) at 2024-11-17 00:05:32 +0000